Vegetation improvement and soil biological quality in the Sahel of Burkina Faso

Abstract

Soil living environment contains macro-fauna that play important role in the soil structure and chemical composition, the degradation process of organic matter and in the resilience of ecosystems. Few studies evaluated the impact of the “re-greening” trend observed in the Sahel on soil biological quality. The objective of this study is to assess the impact of the “re-greening” of the Sahel on soil macro-fauna population and diversity. The method of Tropical Soil Biology and Fertility (TSBF) was used to assess macro-fauna abundance and diversity in different land use types (cropland, shallow land, degraded land and forest). Four sites were selected, in the Sahelian zone of Burkina Faso, with contrasted Normalized Difference Vegetation Index (NDVI). In each site, four repetitions were taken for each land use type. In total, 64 plots samples were used to assess the abundance of macro-fauna. Results showed that there were more individuals (64.92%) and higher macro-fauna density in re-greening zones compared to the degrading zones. There was dominance of Arthropoda phylum (60.85%), Insecta class (59.03%) and Isoptera order (46.97%) in macro-fauna population. There were more species in the shallow land and cropland in re-greening zones and all trophic groups are represented in all sites. Despite this abundance, composition and diversity, it was observed that the re-greening processes have not significantly improved soil biological quality. It is concluded that vegetation improvement might be at the beginning stage in the Sahel, especially in croplands, and clear change of soil biological quality is not perceptible but may be tangible in the future.

Keywords: Macro-fauna, ecosystem, soil quality, re-greening, degradation.